Battery internal temperature sensing battery management system

ABSTRACT

A method is provided. The method is executable by a processor of a battery management system. The method includes sending a first command signal to a multiplexer to cause the multiplexer to select a cell of a battery. The method also includes sending a second command signal to a current source to apply a current to the cell of the battery. The method also includes receiving measurement information based on the application of the current to the cell from a measurement circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of prior-filed, co-pending U.S.Nonprovisional application Ser. No. 15/633,847, filed Jun. 27, 2017,which claims priority to and the benefit of prior-filed U.S. ProvisionalApplication No. 62/354,837, filed Jun. 27, 2016, now expired, thecontents of each of which are herein incorporated by reference in theirentireties.

BACKGROUND

In general, Lithium-ion (Li-ion) batteries are a preferred energystorage and power delivery system for a wide range of applications,including uninterrupted power supplies (UPS), electric vehicles (EV),airplanes, ships, computers, and smart phones. All such equipment andtechnologies demand efficient stored energy use, high power, fastrecharge, and battery safety (e.g., avoiding cell venting, explosion,thermal runaway, and battery fire).

Conventional battery systems provide crude battery monitoring techniquesto support efficient stored energy use, high power, fast recharge, andbattery safety. Yet, conventional battery systems are limited in theirsupport, while failing to provide diagnosis, forensic, and managementcapabilities that properly measure and maintain Li-ion batteries.

For instance, conventional battery systems can only monitor DC cellvoltage, cell current, and surface temperature (T_(surf), usingthermocouples or thermistors), exclusively. Further, some conventionalbattery systems can measure AC impedance, but only at a singlefrequency, typically the amplitude of the impedance at 1 kHz, whichprovides information solely on the electrolyte resistance (R_(s)).Moreover, other conventional battery systems can monitor the batteryvoltage (V_(bat)), but not individual cell voltage. Since T_(surf),R_(s), and V_(bat) do not provide useful information about batterysafety or efficient utilization of the stored energy, monitoring of suchparameters by conventional battery systems cannot fulfill battery safetydemands.

SUMMARY

According to one or more embodiments, a method is provided. The methodis executable by a processor of a battery management system. The methodcomprises sending, by the processor, a first command signal to amultiplexer to cause the multiplexer to select a cell of a battery;sending, by the processor, a second command signal to a current sourceto apply a current to the cell of the battery; and receiving, by theprocessor, measurement information based on the application of thecurrent to the cell from a measurement circuit.

According to one or more embodiments or the method embodiment above, themethod can comprise sending, by the processor, a third command signal toa second multiplexer to cause the second multiplexer to select a currentpath.

According to one or more embodiments or any of the method embodimentsabove, the first command signal and the third command signal can besynchronous commands.

According to one or more embodiments or any of the method embodimentsabove, the measurement information can comprise a cell voltagecorresponding to the cell of the battery.

According to one or more embodiments or any of the method embodimentsabove, the measurement information can comprise a phase shiftmeasurement corresponding to the cell of the battery.

According to one or more embodiments or any of the method embodimentsabove, the measurement information can comprise a cell impedancecorresponding to the cell of the battery.

According to one or more embodiments or any of the method embodimentsabove, the measurement circuit can be electrically coupled to theprocessor and can comprise a gain circuit.

According to one or more embodiments or any of the method embodimentsabove, the measurement circuit can be electrically coupled to theprocessor and can comprise a root means square converter.

According to one or more embodiments, a battery management system isprovided. The battery management system comprises a processor. Theprocessor is configured to send a first command signal to a multiplexerto cause the multiplexer to select a cell of a battery; send a secondcommand signal to a current source to apply a current to the cell of thebattery; and receive measurement information based on the application ofthe current to the cell from a measurement circuit.

According to one or more embodiments or the battery management systemembodiment above, the processor can be configured to send a thirdcommand signal to a second multiplexer to cause the second multiplexerto select a current path.

According to one or more embodiments or any of the battery managementsystem embodiments above, the first command signal and the third commandsignal can be synchronous commands.

According to one or more embodiments or any of the battery managementsystem embodiments above, the measurement information can comprise acell voltage corresponding to the cell of the battery.

According to one or more embodiments or any of the battery managementsystem embodiments above, the measurement information can comprise aphase shift measurement corresponding to the cell of the battery.

According to one or more embodiments or any of the battery managementsystem embodiments above, the measurement information can comprise acell impedance corresponding to the cell of the battery.

According to one or more embodiments or any of the battery managementsystem embodiments above, the measurement circuit can be electricallycoupled to the processor and can comprise a gain circuit.

According to one or more embodiments or any of the battery managementsystem embodiments above, the measurement circuit can be electricallycoupled to the processor and can comprise a root means square converter.

According to one or more embodiments, a system is provided. The systemcomprises a multiplexer configured to select a cell of a battery; acurrent source configured to apply a current to the cell of the battery;a measurement circuit configured to output measurement information basedon the application of the current to the cell; and a microcontrollerconfigured to control the operations of the multiplexer and currentsource via sending command signals.

According to one or more embodiments or the system embodiment above, thesystem can comprise a second multiplexer configured to select a currentpath from the current source to the cell of the battery.

According to one or more embodiments or any of the system embodimentsabove, the multiplexer and the second multiplexer can operatesynchronously to select the cell of the battery and select the currentpath from the current source to the cell of the battery, respectively

According to one or more embodiments or any of the system embodimentsabove, the measurement information can comprise one or more of a cellvoltage corresponding to the cell of the battery, a phase shiftmeasurement corresponding to the cell of the battery, a cell impedancecorresponding to the cell of the battery.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter is particularly pointed out and distinctly claimed inthe claims at the conclusion of the specification. The forgoing andother features, and advantages of the embodiments herein are apparentfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts a schematic of a battery internal temperature sensingbattery management system in accordance with one or more embodiments;

FIG. 2 depicts a process flow of battery internal temperature sensingbattery management system in accordance with one or more embodiments;

FIG. 3 depicts a schematic of a battery internal temperature sensingbattery management system in accordance with one or more embodiments;

FIG. 4 depicts a process flow of battery internal temperature sensingbattery management system in accordance with one or more embodiments;and

FIG. 5 depicts a process flow of battery internal temperature sensingbattery management system in accordance with one or more embodiments.

DETAILED DESCRIPTION

In view of the above, embodiments disclosed herein may include a batteryinternal temperature sensing battery management system, method, and/orcomputer program product (herein BITS-BMS). In general, the BITS-BMS isa safety centric sensor platform for batteries, such as lithium-ionbatteries, with one or more cells. To employ the safety centric sensorplatform, the BITS-BMS utilizes the safety standard and qualificationthat all cells of a battery should match to determine the ‘whether andwhy’ cells are mismatched. Mismatched cells are cells that diverge fromeach other due to aging, use, manufacturing, and/or abuse. Mismatchedcells are first step to endangering the battery, equipment the batterypowers, and an environment in which the equipment is located. Thetechnical effects and benefits of the BITS-BMS include preventingdangerous situations that arise due to cells of the battery beingmismatched at the time cells are selected to make a battery or at thetimes cells become mismatched due to aging, use, manufacturing, and/orabuse. Thus, embodiments herein are necessarily rooted in the BITS-BMSto perform proactive operations to overcome problems specificallyarising in the realm of measuring and maintaining Li-ion batteries.

FIG. 1 depicts a schematic of a battery 99 being monitored and managed aBITS-BMS 100 in accordance with one or more embodiments. The BITS-BMS100 comprises a microcontroller 110, a multiplexer 120, a current source140, and a measurement circuit 150. Further, in the BITS-BMS 100, themicrocontroller 110 can communicate command signals 182 and 183 andreceive measurement information 192.

In general, the microcontroller 110 can be a single integrated circuitcomprising one or more processor cores, a memory, and programmableinput/output peripherals. The multiplexer 120 can be a device thatselects one of several input signals and forwards the selected inputinto a single line. The battery 99 can be a device comprising one ormore electrochemical cells with external connections provided to powerelectrical devices. The current source 140 can be an electronic circuitthat delivers an electric current, such as an alternating current (AC)or a direct current (DC) (e.g., AC current can be used to excite thebattery 99 to procure measurement information for testing/diagnosis and2) DC current can be used for charging). The measurement circuit 150 caninclude a set of measuring instruments, such as a gain circuit, a rootmeans squared converter, etc., which perform measurements on the batteryto obtain measurement information and feed the measurement informationto the microcontroller 110. The measurement information can comprisecell voltage measurements, phase-shift measurement, impedancemeasurements, etc.

The speed and the multi-frequency AC impedance capabilities distinguishthe BITS-BMS 100 from conventional battery systems. The BITS-BMS 100 isa multi-frequency AC impedance-based battery management system (BMS).The BITS-BMS 100 utilizes the measurement circuit 150 to measuresimultaneously amplitude and phase (real and imaginary components) ofthe impedance in a frequency range (e.g., up to 1000 Hz). The BITS-BMS100 utilizes the measurement circuit 150 can also measure a DC cellvoltage. Through the measurements of AC impedance and DC voltage, theBITS-BMS 100 can monitor every cell in a battery in near real time(within seconds). For every cell in the battery, The BITS-BMS 100 canalso utilize the measurement circuit 150 to measures the cell's internaltemperature, internal impedance, cell voltage, state of charge (SOC) andstate of health (SOH), while the battery is at rest or when the batteryis under charge/discharge.

The BITS-BMS 100 utilizes the microcontroller 110 to leverage measuredparameters (e.g., internal temperature, impedance, and cell voltage), tothe send commands 182 and 183, along with other commands to controldevices, such as switches and relays, to adjust the amplitude of thecurrent to charge and discharge the battery safely and rapidly. Notethat a reporting time per cell is adjustable. For example, the reportingtime can be set to a fraction of a second to report only on cell voltageand electrolyte resistance, to less than two seconds to include anodetemperature, and up to 12 seconds to include cathode temperature. TheBITS-BMS 100 can include a small footprint (e.g., 4-inch×4-inchfootprint), utilizes low-power (e.g., requiring 6-V, 750 mA DC power tooperate), and can act as a “standalone” unit with no need for anexternal processor or computer.

Turning to FIG. 2 with reference to FIG. 1, an operation of the BITS-BMS100 is depicted by a process flow 200 in accordance with one or moreembodiments. The process flow 200 begins at block 210, where themicrocontroller 110 sends the command signals 182 to the multiplexer 120to select a cell of the battery 99.

At block 230, the microcontroller 110 sends the command signals 183 tothe current source 140 to apply a current to the cell of the battery 99.The microcontroller 110 sends the command signals 183 to the currentsource 140 to tell the current source 140 to inject a current throughall the cells that are connected in series. Since the microcontroller110 utilizes the multiplexer 120 connect a given at a given time to themeasurement circuit 150, only one cell is measured at a time by themeasurement circuit 150. Note that the microcontroller 110 can makedecisions based on the measurement information that it is fed from themeasurement circuit 150. For example, if a cell internal temperature orcell voltage is too high for a particular cell, then that cell shouldnot receive any current. In turn, the microcontroller 110 can send acommand to a charger to not send any current through the battery 99.

As the current travels through the cell of the battery, the measurementcircuit 150 performs measurements of the battery to obtain measurementinformation and feeds that measurement information to themicrocontroller 110. At block 240, the microcontroller 110 receives themeasurement information based on the application of the current to thecell. Note that, with respect to FIGS. 1 and 2, the microcontroller 110is controlling an AC current source by sending command signals 182 and183 that tell the other components what cell to measure to determinewhether the cells of the battery 99 are mismatched.

FIG. 3 depicts a schematic of a multi-cell battery 299 being monitoredand managed by a BITS-BMS 300 in accordance with one or moreembodiments. The BITS-BMS 300 comprises a microcontroller 310, a cellmultiplexer 320, an AC current source 340. Further, the BITS-BMS 300comprises a measurement circuit 350 comprising a gain circuit 351, aroot means square converter 352, and a gain circuit 353, along with abuffer 352. The BITS-BMS 300 can be connected to a charger 361, acharger control 362, a load 364, and a load control 365. The BITS-BMS300 can comprise status light emitting diodes (LEDs) 372 and a universalserial bus (USB) 373. In the BITS-BMS 300, the microcontroller 110 cancommunicate command signals 382, 383, 384, and 385 and can receivemeasurement information 392, 393, and 394, while the charger 361, theload 364, and the multi-cell battery can be connected to ground. Notethat, for ease of explanation, elements of the BITS-BMS 300 of FIG. 3that are similar to the BITS-BMS 100 of FIG. 1 are not reintroduced.

The gain circuits 351 and 353 increase the amplitude of a signalreceived from the cell multiplexer 320. The root means square converter352 converts the signal received from the cell multiplexer 320 (i.e., analternating current signal) into a direct current signal of equivalentvalue.

According to one or more embodiments, the multi-cell battery 299 can bea 16 cell battery, where the 16 cells are connected in series. The ACcurrent sources can provide an AC current to the multi-cell battery 299based on the command signals 382 from the microcontroller 310. Thecharger 361 can provide a direct current to the multi-cell battery 299to charge one or more of the 16 cells based on the operations of thecharger control 363, which is responding to the command signals 384 fromthe microcontroller 310. The load can withdraw a direct current from themulti-cell battery 299 to utilize power within the one or more of the 16cells based on the operations of the load control 365, which isresponding to the command signals 385 from the microcontroller 310. Thebuffer 354 (also referred to as a buffer amplifier) can provide anelectrical impedance transformation from the multi-cell battery 299 tothe remaining portions of the measuring circuit. The status LEDs 372 canprovide a visual indication of the operations of the BITS-BMS 300, suchas power on, power off, measuring, selecting, charging, etc. The USB 373can provide a communication mechanism for external systems (such as alaptop) to the microcontroller 310, for example, to enable viewing ofthe measurement information and/or programming of the microcontroller310. The BITS-BMS 300 functionalities are limited by the number of cellsin the battery. In other words, the number of cells in the battery canfar exceed the 16-cell example discussed above, and the BITS-BMSfunctionalities are equally applicable to that larger/bigger battery.

In accordance with one or more embodiments, the measurement circuit 350of the BITS-BMS 300 can measure both amplitude and phase shift of the ACimpedance at multiple frequencies. In turn, the measurement circuit 350can characterize each individual cell including the states of the anode,the cathode and, the electrolyte. By coupling the measuring bothamplitude and phase shift of the AC impedance at multiple frequencieswith the BITS-BMS 300 capability of measuring the DC cell voltage, theBITS-BMS 300 achieves effective battery safety and energy managementthat conventional battery systems cannot achieve.

For example, the BITS-BMS 300 monitors multiple parameters in every cellin the multi-cell battery 299. These parameters can include cell voltage(E_(cv)), anode temperature (T_(a)), cathode temperature (T_(c)), R_(s),SOH, and SOC. T_(a), T_(c), R_(s), SOH and SOC are monitored using acimpedance. For monitoring E_(cv), the BITS-BMS 300 can include abuilt-in DC voltmeter that has an input impedance of 2 MΩ. E_(cv) T_(a),T_(c), R_(s) and SOH are monitored while the multi-cell battery 299 isunder charge, discharge or when it is at rest. SOC is monitored onlywhen the multi-cell battery 299 is at rest. To monitor SOC when themulti-cell battery 299 is under charge or discharge, the BITS-BMS 300can be augmented with a COTS DC current meter or a coulometer. TheBITS-BMS 300 can include built-in circuits to prevent short-circuitingthe wirings in any cell and/or the multi-cell battery 299. Note that thebattery voltage and current cannot influence operations of BITS-BMS 300.Note also that the AC and DC measurement capabilities of the BITS-BMS300 provide lithium battery thermal safety and electrical efficiencyfactors, such as diagnostics abilities, forensics abilities, andpower-energy-thermal management.

Diagnostics by the BITS-BMS 300 relate to scenarios where a user desiresto diagnose and group cells into matching sets. For instance,diagnostics by the BITS-BMS 300 can comprise screening and matchingcells before use in assembling a battery and detecting the mismatchedcells after the battery is assembled. Examples of diagnostics caninclude end-of-line diagnostic and screening for cell matching.

Forensics by the BITS-BMS 300 relate to scenarios where the multi-cellbattery 299 was in some kind of incident and safety needs to bedetermined. For instance, if the battery is being used in a vehicle andthe vehicle is in an accident, the BITS-BMS 300 can provide a forensicanalysis to determine with cells are damaged. For instance, becauseforensic diagnostics of Li-ion cells in a damaged battery is inherentlyunsafe and to prevent damage to the multi-cell battery 299 by theBITS-BMS 300, the BITS-BMS 300 can prevent forced charging ordischarging the cells in the multi-cell battery 299 and can prevent themulti-cell battery 299 from forcing a current through the measurementcircuit 350 and the load 365. Also, as a forensic tool, the BITS-BMS 300can conduct diagnostics by evaluating the cells without perturbing thecells and then perturbing the cells with ultra-small AC current signal.The BITS-BMS 300 can also identify burned-out cells in a battery.

Power, energy and thermal management by the BITS-BMS 300 relate toscenarios where use of the multi-cell battery 299. While conventionalbattery systems can provide primitive form of battery management, thepower, energy and thermal management by the BITS-BMS 300 isdistinguished from the conventional battery systems as the BITS-BMS 300conducts impedance measurements.

Note that a Li-ion battery (and an example of the multi-cell battery299) is a device that stores and releases energy, repeatedly up tothousands of times before losing its reliability. Li-ion batteriescontain one or more lithium-ion cells (e.g., 16 cells). In operation,Li-ion batteries store chemical energy in individual cells, and releaseit on demand, not as chemical energy, but mostly as electrical energyand much less as heat energy. The amount of heat energy released dependsupon the environmental temperature; more heat is released when theLi-ion battery is discharged at lower operating temperatures. No matterwhat the environmental temperature is, all cells in the Li-ion batteryare expected to work in concert, each cell releasing the same amount ofelectrical energy and heat energy as its neighbor. The one-cell andmulti-cell lithium-ion batteries also share a common problem.Occasionally, one or more cells in the Li-ion battery may release moreheat than electrical energy, causing the cell(s) to vent, explode, catchon fire, and propagate the problem to the neighboring cells. To preventthese problems, the power, energy and thermal properties of every cellin the Li-ion battery is carefully managed by the BITS-BMS 300. That is,the BITS-BMS 300 can monitor the form of energy (electrical and heat),and the rate of energy release, control the rate of energy deliveryduring discharge and the rate of energy intake during charge, and reportand raise an alarm when the rate of release or intake exceed the presetlimit.

FIG. 4 depicts a schematic of a BITS-BMS 400 in accordance with one ormore embodiments. Note that, for ease of explanation, elements of theBITS-BMS 400 of FIG. 4 that are similar to the BITS-BMS 100 of FIG. 1and BITS-BMS 300 of FIG. 3 are not reintroduced. The BITS-BMS 400comprises a current multiplexer 420 that operates with respect tocommand signals 482 received from the microcontroller 110.

Turning to FIG. 5 with reference to FIG. 4, an operation of the BITS-BMS400 is depicted by a process flow 500 in accordance with one or moreembodiments. The process flow 500 begins at blocks 510 and 520, whichcan operate simultaneously. That is, the microcontroller 110 can sendthe command signals 182 and 482 to the multiplexer 120 and the currentmultiplexer 420 to respectively select a cell of the battery 99 and toselect a current path from current source 140 and the battery 99. Thus,the multiplexer 120 and the current multiplexer 420 perform asynchronous operation. At block 530, the microcontroller 110 sends thecommand signals 183 to the current source 140 to apply a current to thecell of the battery 99 in accordance select path by the currentmultiplexer. At block 540, the microcontroller 110 receives themeasurement information based on the application of the current to thecell.

Example embodiments of the present invention may be a system, a method,and/or a computer program product at any possible technical detail levelof integration. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one more other features,integers, steps, operations, element components, and/or groups thereof.

The descriptions of the various embodiments herein have been presentedfor purposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments. The terminologyused herein was chosen to best explain the principles of theembodiments, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method executable by a processor of a batterymanagement system, the method comprising: sending, by the processor, afirst command signal to a multiplexer to cause the multiplexer to selecta cell of a battery; sending, by the processor, a second command signalto a current source to apply a current to the cell of the battery; andreceiving, by the processor, measurement information based on theapplication of the current to the cell from a measurement circuit,wherein the measurement information comprises a cell voltage.
 2. Themethod of claim 1, the method comprising: sending, by the processor, athird command signal to a second multiplexer to cause the secondmultiplexer to select a current path.
 3. The method of claim 2, whereinthe first command signal and the third command signal are synchronouscommands.
 4. The method of claim 1, wherein the cell voltage is a singlecell voltage corresponding to the cell of the battery.
 5. The method ofclaim 1, wherein the measurement information comprises a phase shiftmeasurement corresponding to the cell of the battery.
 6. The method ofclaim 1, wherein the measurement information comprises a cell impedancecorresponding to the cell of the battery.
 7. The method of claim 1,wherein the measurement circuit is electrically coupled to the processorand comprises a gain circuit.
 8. The method of claim 7, wherein themeasurement circuit is electrically coupled to the processor andcomprises a root means square converter.